1. Field of the Invention
The invention relates to a contact device for low voltage switch devices. More particularly, it relates to contactors with at least two stationary contact bars having contact pieces, as well as at least one electrically-conductive contact bridge which is disposed in a contact bridge support and is movable by means of a spring force.
2. Description of the Prior Art
Contact devices of the aforementioned type are known, for example, from DE-AS 25 25 467, CH-PS 247 323 and CH-PS 451 288. In these contact devices, the contact bridges consist of massive bars engaged at the center thereof by of a single contact spring. It has been attempted by means of numerous structural measures to overcome the problem of burn-off of the contact pieces, for example, by pivot movements of the massive contact bridge with the movable contact pieces, or by roll motions of the movable contact pieces on the stationary contact pieces. However, a common disadvantage of all of these known contact devices is the combined effect of the relatively large movable mass of the contact bridge with the movable contact pieces. This mass is required for this type of structure, because the contact bridge in the form of a massive bar must be so designed that the required contact pressure forces are sufficiently transferred from the contact pressure spring. This results, on the one hand, in a large mass of material and, on the other hand, in a switch-on impact which, in actual practice, cannot be prevented. In order to keep these disadvantages to a minimum, it has been attempted to keep the contact bridges as short as possible. However, this results in other problems, for example, construction difficulties, insufficient switch safety, poor accessibility to all individual parts, and the like.